In a processing (electronic and/or micro-electronic) system of analog-type electrical signals (hereinafter, for brevity's sake simply being referred to as analog signals), a switch module (switch) is typically employed in particular applications, which is capable of enabling and inhibiting the transfer of an analog signal from a source module to a user module.
For example, in an Analog-to-Digital converter system ADC, the switch module is employed, as it is known, for a sampling function, by storing the analog signal value while the switch module results to be in the so-called “off” state.
In a Digital-to-Analog Converter system DAC, the switch module is also employed for the transfer of an analog signal towards an amplification stage, in predetermined time instants in which the same results to be in the so-called “on” state.
A helpful function is a switch module that is used in such systems is that of transferring the analog signal, on which it operates, in q reliable way. In other words, it is desired that the noise and/or the distortion added by the switch module to the transferred analog signal are reduced as much as possible (being ideally equal to zero).
Typically, a switch module operating on analog signals is driven by a corresponding control digital circuitry, having the task of generating control logic signals of the switch module and to provide to it, through a driving device, a driving electrical signal, on the basis of the above-mentioned control logic signals, to allow the opening (state “off”) or the closure (state “on”) of the switch module.
Such a driving device has the drawback of further perturbing the analog signal on which the switch module operates, adding noise and/or distortion to it, even in a significant amount. This is due to the fact that such a driving device takes the driving electrical signal from a supply circuitry internal to the electronic and/or micro-electronic system for the processing of analog electrical signals.
In particular, with respect to such supply circuitry, it is pointed out that such a system usually comprises two different types of circuitry: analog supply circuitry, to which the system analog circuitry is electrically connected; and digital supply circuitry, to which the system digital circuitry is electrically connected.
As it is known, the analog supply is capable of providing, in a plurality of analog supply terminals, a first and a second analog supply potentials, while the digital supply is capable of providing, in a plurality of digital supply terminals, first and second digital supply potentials.
Such first supply potentials (both analog and digital) can originate from, or coincide with, first external supply potential, having a same nominal value one to the other. Similarly, such second supply potentials (both analog and digital) can originate from, or coincide with, a second external supply potential, having a same nominal value one to the other. Such first and second external supply potentials can be, for example, obtained from a battery.
However, the real instantaneous values of such supply potentials can vary, departing from the nominal value. Particularly, the digital supply is usually characterized by a higher switch noise, associated to the switching operations of the digital components connected thereto.
The availability of two supply circuitries is a compromise that is usually adopted among the availability of an individual supply circuitry, that would lead to a degraded performance mainly due to excessive undesired mutual influences determined by the different operating modes of the digital components and the analog components, and the availability of a number of different supply circuitries, to which single subsystems of the system would refer, which would improve the performance by minimizing the mutual influences, but would lead to unacceptable costs and space waste.
Typically, the switch module control circuitry is connected to the digital supply. In such a scenario, the corresponding driving device is to be connected to the digital supply, which may be the last control circuitry component before the switch module, and which directly interacts with the same switch module through the driving electrical signal.
The driving device, connected to the digital supply, has a drawback in that it transfers at least partially on the switch module, and therefore on the analog signal on which it operates, the switch noise that is present on the digital supply. Particularly, the noise is present both in the periods in which the switch module is “on” and in those in which it is “off”.
Therefore, the general need of employing a driving device that minimizes the noise transferred from it to the switch module is strongly felt.
A known approach to cope with such drawback is the use of a driving device that is connected to the analog supply (which, as it is known, is already available) instead of being connected to the digital supply. This solution exploits the advantage that the analog supply, as it is known, has a noticeably lower noise compared to the digital one, since the switch noise of the digital components, which are connected to the digital supply, is not present therein.
However, such solution, while on one hand reducing the drawback due to the switch noise, has the disadvantage of introducing further distortions on the analog signal on which the switch module operates. This is due to the fact that the driving device switching currents, during the time intervals associated to the switch module transition from one to the other of the relative states (“on”, “off”), may be suddenly variable.
In this scenario, such currents flow through the analog supply terminals, thus perturbing the already mentioned analog supply potential values. In fact, such switching currents create undesired voltages on the non-zero resistances of the internal supply paths. Furthermore, the perturbations induced by the switching currents on the analog supply, caused for example by stray phenomena, particularly related to the inductance, on the analog supply bondings, are particularly serious. In fact, besides distorting the analog signal on which the switch module operates, they affect the operation of the entire system analog circuitry, connected to such supply, thereby reducing the performance thereof.
The object of the present disclosure is to provide an improved system for the processing of analog electrical signals.